Short oil alkyd resin having an unusually short air drying time



United States Patent Office 3,329,634 Patented July 4, 1967 3,329,634SHORT OIL ALKYD RESIN HAVING AN UN- USUALLY SHORT AIR DRYING TIMECharles J. McWhorter, Glen Ellyn, and Edgar L. Clark,

Oak Park, Ill., assignors to Commercial Solvents Corporation, acorporation of Maryland No Drawing. Filed Jan. 25, 1963, Ser. No.253,975 2 Claims. (Cl. 260-22) Our invention relates to alkyd resins andin particular to novel short oil alkyd resins useful in industrialcoatings designed for very short air drying times.

In industrial coatings, the properties of the shortest possible airdrying time consistent with good flexibility and exterior durability arevery desirable for many applialkyd with the property of being soluble inaromatic solvents, e.g. xylene. Preferably, the alkyd comprises thereaction product of 14.6 to 15.0 weight percent of pentaerythritol, 14.6to 15.0 weight percent of trimethylolethane, 31 to 33 weight percent ofphthalic anhydride, to 12 weight percent of benzoic acid and 27 to 28.5weight percent of dehydrated castor oil fatty acids.

The novel alkyd resins of our invention are prepared by reacting thepolyols and acids by conventional methods, e.g. by heating the mixtureof ingredients until the desired acid number and viscosity are obtained.Preferably, all the ingredients are admixed in the presence of asuitable solvent, for example, xylene, and the ingredients heated to atemperature of about 440 to 470 F., over a cations and numerous productshave been formulated in 15 period of about 6 to 9 hours until an acidnumber below an attempt to meet this objective. We have now foundab01lt6is i dthat a short oil alkyd resin comprising the reaction prod-The y Of our invention n be us as V hicles uct of a polyol mixture ofequal parts by weight of pentato P p Coating formulations, Paints,lacquers, erythritol and trimethylolethane and an acid mixture ofvarnishes, enamels, y inclusion With suitable Pigments, phthalicanhydride, benzoic acid and dehydrated castor driefs, solvents,dihlehts, -i ill a manner known to t oil fatty acids provides anunusually short air drying time The aikyds are Particularly useful informulations, combined with good flexibility and unusually good ex-Particularly gloss formulations, designed to be applied t io d bilitwhere the coating is to be air dried. Such formulations I i surprisingth t h a gross ti as 1 t 1 b are particularly desirable in assembly lineoperations weight of pentaerythritol and trimethylolethane should Wherequick P g is desired, Where a surface is provide such desirable resultssince there is nothing of p y On an assembly iihe and it is desired thatthe theoretical significance about this ratio. It is particularlyCoating y y the time, 20 minutes, the article surprising since the useof an equal hydroxyl ratio, i.e. reaches the d f th lin SO that it canbe lifted off equal numbers of pentaerythritol and trimethylolethane yhand Withollt leaving Prints on the Coating and then hydroxyl groupspresent in the charge, which is equivalent 3O stacked f a ll i nt timeto dry Completely, e.g. one to a weight ratio of approximately 8 to 9 or0.88 to 1, hour, before packing. Such articles include, for example,provides an inferior air drying time. Moreover, the use water heaters,electrical lighting fixtures and imitation f a molar ratio f 1 to 1 hi hi equivalent to a i h tile-wall board. Since the novel alkyds possessunusual r ti of b ut 9 t 8 o 1,12 t 1, provides a prcduct durability,i.e. ability to stand weathering, they are also hi h gels b fo e the d ied oid' u he f th alkyd particularly useful for fast drying exteriorcoatings, such re i a b h d, W h o explanation f r th as power lawnmower finishes and automotive re-finishing. observed superiority of theformulation using equal parts The novel alkyds 0f y invention Will befurther il by weight of pentaerythritol and trimethylolethane. ire-ted ythe following eXamPies in Which alky s Wi h The product f ou i ve ti n ia ho t il alkyd resin different ratios of pentaerythritol andtrimethylolethane comprising the reaction product of a polyol mixture of40 were prepared and tested in enamels for drying time and equal partsby weight of pentaerythritol and trimethylr ili y. olethane with an acidmixture of phthalic anhydride, ben- Examples 1 t0 3 zoic acid and 27 to28.5 weight percent of dehydrated castor oil fatty acids based on thetotal of the polyol and Alkyds were Pf from pentaerythritol, y acidmixture. Larger amounts of the fatty acid do not oiethane 'phihaiicanhydride, benzoic acid and yprovide a ffi i tl Short air drying timeThe dehy drated castor 011 fatty acids with varying amounts of dratedcastor oil fatty acids are preferably those containpentaerythritoltrimethylolethane The alkyds were ing a low amount of hydroxy acids,preferably not more P ep 111 a 5 liter, 3 necked flask q ipp d i h anthan about 3 to 8 percent f hydroxy acids P f bl ag1tat0r, thermometer,and solvent reflux head with water phthalic anhydride is used althoughphthalic acid can be Separator and Overflow return for y Ail theingrediused. The amounts of phthalic anhydride and benzoic acid ehtsWere Charged into the flask and heated slOWiy to are adjusted to obtainthe desired resin hardness without 470 F. over a four hour period.Heating was then congelation. Also, the benzoic acid provides theresulting tinued until an acid number below 6 and a cure of 36 TABLE IExample 1 Example 2 Example 3 Weight Weight Weight percent 1 Gramspercent 1 Grams percent 1 Grams DCO Fatty Acids 27.9 558 26. 6 538 27.9558 Phthalie Anhydride 31- 6 632 33. 2 672 31. 6 632 Pentaerythritol 14.8 297 13. 9 282 15 7 314 Trimethylolethane 14. s 297 15. 6 316 14. 0 281Benzoic Acid 10.3 216 10. 7 216 10.3 216 Xylol PE/TME weight ratio 9 3PE/IME hydroxyl ratio 9 7 PE/TME mol ratio 1/1 Viscosity, Gardner-Holdtat 50% NV in Xylol Z1 Y Gelled Tack free time 20 35 1 Based on the totalamount benzoic acid.

fatty acids, phthalic anhydride, pentaerythritol, trimethylolethane andseconds on a 392 F. cure plate was reached. The alkyds were tested fordrying time in a clear solution of the xylol in which they wereprepared. The dehydrated castor oil fatty acids had the followingcharacteristics: average molecular weight 280, acid number 197-202,saponification number 198-204, iodine number (Wijs-300% excess) 150160,titre C. maximum, and color 4 Gardner maximum. The results are tabulatedin Table I.

The results show that the alkyd of Example 1 with a pentaerythritol totrimethylolethane weight ratio of 1:1 had a tack free time (a measure ofprint resistance) of only minutes while the alkyd of Example 2 with aweight ratio of 8:9 or 0.88:1 (equivalent to an equal hydroxyl ratio)had a tack free time of 35 minutes, which is sufficiently high to beimpractical for quick-drying coating operations. The alkyd of Example 3with a weight ratio of 9:8 or 1.12:1 (equivalent to an equal molarratio) gelled long before the desired acid number was reached. Thisindicates the extreme sensitivity of a slight shift away from the 1:1ratio and the criticality of the 1:1 ratio in obtaining sufficientlyearly print resistance.

Examples 4 and 5 The alkyd of Example 1 was made into a white applianceenamel and tested against a similar enamel made with a fast dryingpremium commercial alkyd. The composition of the enamels in parts byweight were as follows:

Enamel Composition Ex. 4 t Ex. 5

Titanox R A 50 1 300 300 Commercial Alkyd 600 Alkyd of Ex. 1 600 Xy 124124 6% Cobalt Drier 1. 75 1. 75 6% Zirconium Drie 3. 5 3. 5 Exkin #2(anti-skin) l. 75 1. 75

1 Rutile titanium dioxide pigment.

After 330 hours 84 Examples 6 t0 8 The alkyd of Example 1 was made intoa green enamel and tested against a similar enamel made with a urethanemodified commercial alkyd (alkyd #1), a premium product highlyrecommended for exterior durability, and against a similar enamel madewith another commercial alkyd (alkyd #2) with a long record of excellentperformance in exterior exposures. The enamels were tested in aweatherometer as in Examples 4 and 5. The composition of the enamels inparts by weight and the results of testing were as follows,demonstrating the unusual durability of the alkyd of Example 1.

Enamel Composition EX. 6 Ex. 7 Ex. 8

Western Dry Color Co.

#348 Chrome Green 96 96 96 Lecithin 1. (i 1. 6 1. 6 Xylol 152 144 152Commercial Alkyd #1. 544

Commercial Alkyd #2. Alkyd of Ex. 1 Gloss after 286 hours weatherometerExcellent References Cited UNITED STATES PATENTS 2,915,488 12/1959 Kraftet al. 26022 DONALD E. CZAIA, Primary Examiner.

LEON J. BERCOVITZ, Examiner.

R. W. GRIFFIN, Assistant Examiner.

1. A SHORT OIL ALKYD RESIN COMPRISING THE REACTION PRODUCT OF 14.6 TO15.0 WEIGHT PERCENT OF PENTAERYTHRITOL, 14.6 TO 15.0 WEIGHT PERCENT OFTRIMETHYLOLETHANE, 31 TO 33 WEIGHT PERCENT OF PHTHALIC ANHYDRIDE, 10 TO12 WEIGHT PERCENT OF BENZOIC ACID AND 27 TO 28.5 WEIGHT PERCENT OFDEHYDRATED CASTOR OIL FATTY ACIDS.